What does this PR do?:

This PR is a scan-build (static analysis) warning cleanup. The changes span 29 files and fall into these categories:

Signed/unsigned comparison fixes (most of the work)

• Loop variables changed from int to size_t where iterating over std::vector / array sizes (flightRecorder.cpp, symbols_linux.cpp, livenessTracker.cpp, codeCache.cpp,
  reservoirSampler.h)
• Mixed signed/unsigned comparisons cast explicitly: size_t(r), (uint32_t), (int)sizeof(...), etc. (os_linux.cpp, perfEvents_linux.cpp, libraries.h, vmStructs.cpp)

Constructor initializer list ordering (fixes warnings about out-of-order init)

• Profiler, PidController, BaseWallClock, CallTraceHashTable, Arguments constructors reordered to match declaration order

Type correctness

• VMStructs::_tls_index changed from int to pthread_key_t (vmStructs.h/cpp)
• FrameDesc::cfa changed from int to u32 (dwarf.h)
• HeapUsage::_maxSize comparison uses size_t(-1) instead of -1

ODR / linkage fixes (functions defined in headers)

• static → inline for jniExceptionCheck, convertJvmExecutionState, cpuHasGoodTimestampCounter
• static Context DD_EMPTY_CONTEXT moved from header to .cpp to avoid multiple-definition issues

Dead code removal

• Removed unused orig_trapHandler, range_for_fbase(), _min(), and blank private: section

Minor fixes

• javaApi.cpp: dumpContext guarded with #ifdef DEBUG, format specifiers corrected (%llu for u64)
• Makefile: -DEBUG → -DDEBUG (was a typo — the define was never actually set)
• Whitespace/indentation cleanup in several files

Motivation:
Code cleanup and improve maintainability.

Additional Notes:

How to test the change?:

• CI tests

For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.
• JIRA: PROF-14135

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